The present invention relates to plastic injection molding and, more particularly, to plastic injection molding wherein a container has a hollow channel integrally formed to its walls.
Some plastic containers are formed with an inlet orifice and an outlet orifice so that a fluid can circulate to and from the container thus allowing recirculation of the fluid to or from an external device. An example of such plastic containers is the cooling water reservoir used in the cooling system of an internal combustion engine; this cooling water reservoir is used not only for storing an overflow of cooling water but also for insuring a recirculation of a part of the cooling water to the reservoir to thereby separate and remove air and vapor from the cooling water in the reservoir. Such reservoir is formed with inlet and outlet ports each adapted to receive the connection of a hose or a tube. One such tank may be found described in U.S. Pat. No. 5,111,776 issued May 12, 1992 to Matsushiro et al.
The space available to locate a reservoir tank under the hood of a vehicle is very restricted and the presence of these hoses is often encumbering.
In a degas tank such as described in U.S. Pat. No. 5,329,889 issued Jul. 19, 1994 to Caldwell, there is shown a container having inlet and outlet ports to which is connected a series of tubes for connection to a combustion engine and a radiator. Evidently, the presence of these tubes take up an important part of the space available under the hood of a vehicle wherein many devices are lodged.
It is an object of the present invention to provide a container made of plastic material which has, integrally formed to its walls, one or more channels allowing the circulation of a fluid.
The present invention is therefore concerned with providing a plastic container wherein a channel is formed integrally with the walls of the container. The channel may extend along the outer wall of the container, or along its inner wall, or along both the inner and outer walls. Once this channel is formed, extremities thereof are cut through so that a fluid may circulate throughout.
The present invention therefore relates also to a method of making such plastic containers having walls with fluid circulatable channels integrally formed therein. The method comprises broadly the successive steps of:
injecting a molten thermoplastic material in a mold cavity having a channel configuration to define, in a container part being molded, walls with thicker portions that define a rib configuration;
injecting a pressurized fluid in the rib configuration to displace molten material therein and to thereby form a hollow channel therein;
cooling the container part being molded;
removing the molded container part from the mold cavity;
cutting through the hollow channel at two spaced locations to form inlet and outlet openings to the channel to thereby enable circulation of a fluid therethrough.
The fluid that is injected may be a gas or a liquid. In the case of a gas, venting is required prior to removing the container from the mold cavity. If a liquid is used, pressure release may or may not be required depending on the liquid and procedure used.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that this detailed description, while indicating preferred embodiments of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.